As recently created, the landfill site of Oujda, Morocco receives an annual flow of municipal solid wastes of 140000 tons. It became clear that the leachate storage ponds were undersized compared to the actually emanating flows. With no adequate treatment, the storage time of leachates in deep and anaerobic ponds increase and produce olfactory nuisances directly affecting the air quality of the nearest agglomerations. The monitoring of leachate flows during a year, showed the daily average production of 126 m3 (annual cumulative leachate is 46800 m3). Thus, highest volumes were recorded during the summer season (4716 m3 in July 4945 m3 in August, and 4927 m3 in September) with a monthly average rate of 3700 m3. In addition, the monitoring of leachate flows exhibits annual variations. Simultaneously, the MSW's typology and moisture content study showed the dominance of organic matter (73%) and high moisture content (63.5%). The results obtained are an essential asset for any decision in order to achieve appropriate leachates treatment with a possibility of recirculation into the landfill cells to enhance removal of their toxic contents.